Almost 14 million red blood cell units are transfused in the US each year. Blood transfusion is a critical therapy in modern medicine, but concerns about misuse and overuse have been a hallmark of transfusion medicine for over a century. Transfusions place patients at risk for transfusion-related adverse events such as volume overload and are costly to the health care system. Measuring and tracking transfusion rates is necessary to assess the impact of policies to promote evidenced-based transfusion practices. Inpatient insurance claims data represent a low cost and accessible source for measuring transfusion rates, but two previous studies have reported conflicting results regarding the sensitivity of claims for capturing transfusions. In the face of uncertainty about the reliability f claims data, researchers and policymakers may hesitate to use claims data for conducting transfusion-related health services research and monitoring compliance with evidenced-based transfusion standards. Using a unique, multi-hospital dataset that includes laboratory, tissue bank, and billing records, we will determine the sensitivity and specificity of claims data relativ to tissue bank records (the gold standard) for measuring the receipt of a transfusion. The FOCUS trial, published in the New England Journal of Medicine in 2011, found that patients undergoing surgical repair of a hip fracture randomized to a liberal transfusion strategy, where transfusions were provided to maintain hemoglobin levels above 10 g/dL, did not have better outcomes than patients randomized to a restrictive transfusion strategy, where transfusions were provided to maintain hemoglobin levels above 8 g/dL. A secondary goal of the project is to determine whether transfusion rates declined following the publication of the FOCUS trial. We will use the hospital data and state inpatient discharge datasets to assess trends over time in transfusion rates among patients similar to those who participated in the FOCUS trial. The results will be useful for determining the need for additional interventions to increase the uptake of findings from the FOCUS trial.